James l



(No Model.)

J. L. MQQUARRIE. TELEPHONE GIEGUIT AND APPARATUS.

No. 443,145. Patented Bea-23, 1890.

W irl/asses. I Inventor 5 M W01 %%@m wit v UNITED STATES PATENT Fries JAMES L. MCQUARRIE, OF BOSTOY, MASSACHUSETTS, ASSIGNOR TO THE NEW ENGLAND TELEPHONE AND TELEGRAPH COMPANY, OF SAME PLACE.

TELEPHONE CIRCUIT AND APPARATUS.

SPECIFICATION forming part of Letters Patent No. 443,145, dated December 23, 1890.

' Application filed June 27, 1890. Serial No. 356,949. (No model.)

To all whom it ma/y concern.- Be it known that I, JAMES L. MCQUARRIE, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Telephone Circuits and Apparatus, of which the following is a specification. v

. To obtain inductive neutrality in telephonecircuits it has for some time been customary to construct such circuits as otherwise would be exposed to inductive disturbances upon the plan patented to David Brooks February 22, 1881, No. 238,195, in which, instead of being completed through the earth, the several exposed circuits are provided with a closelyadjacent and substantially parallel metallic return-wire, whereby the induced currents developed on either side of the circuit from the source of disturbance are neutralized by the equal but opposite currents developed by the same source on the other side of the circuit.

It is not new on economical considerations to form combinations of a plurality of lines which are ordinarily single Wire or earth return-circuits, each supplying its own sub-sta tion insuch a way that said stations of either one of a pair of such circuits may, in combination with its own line, use the line of the remaining circuit of said pair, and so form of the two, as occasion may require, a temporary metallic circuit. Nor is it new, also, on the score of economy to connect a plurality of sub-stations with a regularly-constituted metallic circuit in such a waythat each sub-station while using thecircuit for conversational purposes shall have a clear and balanced metallic circuit unencumbered by interposed electromagnets. v

This invention relates to these general classes of telephone-circuits.

In all metallic circuit systems with which I am familiar there are certain practical drawbacks, which by myinvention I aim to avoid or overcome, and, generally stated, its object is to provide a metallic telephone-circuit which may be common to a plurality of sub-stations, in which each sub-station has at all times the use of a metallic circuit with all the advantages inherent therein, in which each sub-station may be called from the central station without giving the alarm at the other station, and may also signal the central station without signaling the other station, the calls from both sub-stations being received upon the same call-receiving instrument at the central station, and in which but one spring-jack or other switching device or annunciator per double-wire circuit is required.

In pursuance of this object my invention comprises, in a telephone-exchange, a metallic circuit extending from a central station to two sub-stations, call sending and receiving apparatus at both central and sub stations, means consisting of special circuit arrangements at the sub-stations and special switching appliances associated with the call-generator at the central station, whereby the cen-' tral station may signal either sub-station independently and individuallywithout alarming the other, and appliances at each substation whereby calls are enabled to be sent from either to the central station without at fecting, also, the call apparatus at the other sub-station.

More specifically, the essence of my inveri tion consists in placing the call apparatus of the most distant sub-station in the actual normal metallic main-line circuit, including the call apparatus of the sub-station nearest to the central station in a separate branch diverging at the said substation from one of the 1nain-circuit wires and extending therefrom after passing through the said interme' diate-station call apparatus, to earth at the most distant substation, and in providing a switching device at the central stationwhereby the call-generator there may at will be included in the metallic circuit of the main line to ring the most distant statioirbell, andl alternately may be included in an earth-coin pleted circuit to ring the bell of the nearer station.

It consists, also, in combining with the two wires of the main line metallic circuit and with a single spring-jack switch and annunciator at the central station a circuit-changing device at the intermediate station, Whereby when it is desired to send a call to the central. station the said call apparatus may be transferred from the earth-branch exterr sion to the metallic circuit, and at the same time the main line leading to the station beyond is disconnected, so that the call-signals are sentin the direction of the central station only.

It consists, also, in combining with the said instrumentalities automatic and manual circuit-breakers in the earth branch extension at the most distant station to provide against the contingency of an accidental earth fault at some point on the main circuit, and the possible confusion in sending and receiving call-signals resulting therefrom, and to aid, also,in perfecting the electrical balance of the talking-circuit.

It consists, also, in the special connections and circuit arrangements whereby the telephones at the sub-stations may be combined with the foregoing devices in such a waythat they shall be on open circuit when not in use and connected when in use with both of the metallic-circuit wires.

The drawing which accompanies and forms a part of this specification is a diagram clearly indicating the features and scope of my invention. It shows a double wire or metallic circuit L, extending from a central station 0 to a terminal sub station 15, and passing through and serving also an intermediate substation A. At the central station, as is well understood, a number of such circuits center, these being indicated by the presence in the diagram of the detached portion of an independent substation circuit L Each circuit is furnished with a single spring-jack or other like connecting device I) and a call-receiving annunciator a. A key-board K may be provided with a number of pairs of connectingcords 0, each comprising two flexible conductors c and c and for each pair of connecting-cords a pair of circuit-changers 7;, which when depressed act to send outgoing call-signals, while when remaining un pressed they allow each of the two flexible conductors of one of the connecting-cords to electrically join directly one of the conductors of the other connecting-cords, and by means of these double cords the two wires of any metallic telephone-circuit may be connected with the two wires of any other metallic telephone circuit. For this purpose the outer end of each core of a pair is furnished with a plugconnector arranged with two conducting parts forming, respectively, terminals of the two inclosed conductors of each cord. The two conductors c unite with the central conductingstem of their respective plugs, and these terminate in the rounded tip 11' of the plug, and the two conductors 0 passing through their respective cords, are attached at their respect- 1V0 plugs to the metallic sleeve or outer por tion 19 of the plug-stem. The tip 21 and sleeve 19 are of course insulated from each other, and the insulation is indicated by the ring 7'', which appears in the unconnected plug immediately behind the convex tip. 'hen the plugs are inserted in the spring-jacks, the tip breaks the original contact thereof and makes contact itself with the spring portion thereof, while the sleeve portion of the said plug in turn makes contact with the frame portion of the said jack, it being understood that the said spring and frame of the said springjack are or may be for the purposes of this case regarded as being respectively the terminals of the metallic main circuit represented by the said spring-jack.

In the key-board K the ends of the two flexible conductors 0, each extending from the tips of their respective plugs, are attached to contact-springs (1, while the other conductor 0 of each cord of the pair is in like manner attached to a similar contact-spring (Z The springs d and (Z of each cord are controlled by one of the circuit-changers 7;. \Vhen the circuitchangcrs are undepressed,the said springs of both cords rest on front contact-points. The contact-points on which rest the springs (Z are united by the wire 12, and the points forming the resting-contacts of the springs cl are united through the wire 13, and it will 110w be seen that when the two plugs of a pair of connecting-cords are inserted in the springjacks of a pair of metallic circuits the path of the connecting-link through the key-board is from the tip p of one through the cond uctor 0 thereof, spring (1', wire 12, spring (1', and conductor 0 of the other to the tip of the remaining plug, and that the two sleeve portions of the two plugs are united through the two sections of conductor c the two springs (1 and the wire 13 uniting the said springs. The operators telephones T and tare included in a bridge from the wire 12 to the wire 18, and when so placed do not interfere with through communication, while both lines can, if desired, be readily communicated with. The said telephones will of course in practice be common to a number of connecting-loops, and will be provided with suitable switches to disconnect them from any special pair when two subscribers lines are connected. The contact-springs d and (7 controlled by the circuit-changers 7-, have reverse contactpoints, against which they are caused to impinge when the circuit changers are depressed. Those which are marked 6 and e are respectively the back contacts for the terminal springs (Z of the sleeve-conductors, and are united together by a wire 1% and both by wire 15 to a contact-button 1 of a hand-switch S, which in practice is, for the convenience of the operator, placed on the table E, and those which are designated 9 and g are the back contacts for the terminal springs (Z of the tip-conductors. They are united by a wire 16, and this by a wire 17 is connected with one terminal of a call-generator G, which may be of any desired type, although I prefer a power-driven magneto. The other pole or terminal of the said generator connects by wire 18 with the lever Z of IIS by a ground wire.

the switch'S, andthe remaining contact-butto11 of the said switch is connected with the earth By means, then, of this switch the call-generator can be closed either in an earth-completed or in a metallic circuit.

When the switch-lever is placed on the button '0 the circuit-changers 70, or either of them, being depressed, the two terminals of the generator are virtually extended to the tip and sleeve of the corresponding plug, and

call-signals can be sent over the two wires of a metallic circuit with which the said tip and sleeve may be connected; but if the switchlever be placed on the buttonvit will be seen that the springs (1 only are connected with the generator, the other pole of said generator being grounded, and that the tip only of a plug connected with the operating-spring d becomes the generator-terminal. Under such circumstances, that wire of a metallic circuit only which comes in contact with the tip of the plug is connected with the generator, and over it only will the outgoing call be sent. If any earth branch be connected with the said wire and signal-receiving devices be included in said earth branch, it is evident that the said devices will be responsive to a call so sent, although they will be inert when calling-currents are caused to traverse the 1116- tallic circuit, and in the same way call-receiving devices included in the circuit of the two line-wires closed at the ends as a metallic circuit will respond when the generator is in cluded in said metallic circuit, but will be irresponsive to the generator when grounded in the manner described above.

I will now trace out the line-circuits from the central station 0 to the substations A and B, and as the principle of the invention is the same without regard to the number of circuits it is sufficient to show and describe a single circuit. At each sub-station there is the usual telephone outfit, comprising the transmitting-telephone T, the receiving-telephone t, a call-bell D, acall-generator G for sending outgoing calls, an automatic switch I-l, serving as a telephone-support and acting in its normal position to keep the telephones disconnected, the transmitter battery-circuit open, and the bell branch in circuit, and in its converse position to disconnect the calling apparatus to close the local-battery circuit and to connect the telephones. The switch ll at substation B has an additional function to whichI will hereinafter advert. The wires 8 and 9 at stations A and B are the conduct ors of the transmitter local circuit. Leading from one pole of the battery N the wire 8 passes to the movable portion 1 of a circuitcloser for this circuit operated by the automatic switch-bar h from the other or fixed contactm of said circuit-closer. The other wire 9 of the local circuit passes to the electrodes and primary helix of the inductioncoil in the transmitter in a manner well understood, and the circuit then returns by the wire 10 to the other pole of the battery N.

These connections are identical at both stations.

The main line of the metallic circuit L when at rest is from the jack-spring s, with which the plug-tip when inserted makes contact by main wire 1 straight to the most distant station B. There it is permanently attached to the switch-bar h. The line being at rest the switclrbar h makes contact with the stop 2' and the circuit continues thereby and by wire 21 to the call-generator Gr, wire 22, call-bell D, and then by main-line wire 2 to the intermediate sub-station A. Here there is a manual circuit-changer J, forming, practically, a double key, and consisting of two conducting springs or stems j and m mechanically united, but electrically separated by the insulating-blocks z and z, and both governed by the same press-button it. hen at rest, this key has its stem j in contact with a conducting-block, forming a back contact therefor, but capable of being disconnected therefrom, and serving also as a front coni tact for the other stem m when the press-button is pushed. The line 2 from station B is united to the stem j of this key, and thus continues by way of the conducting-block out, passing therefrom to the central station G, where it reaches the spring-jack from which it started, connecting with the frame f thereof. One of the wires of the said circuit thus connects with the jack-spring s and the other with the jack-frame f. The call-communicator a of this line is looped by the wires 19 and 20 between the insulated contact-screw q of the spring'jack on which the spring 3 normally rests and the jack-frame f, and when the plug 13 is withdrawn from the jack is in the circuit.

The above description shows that the callbell of station B is included in the direct metallic circuit L, and hence that calls sent from the central station 0 over said circuit (the switch S being placed on the button "0 will operate the said bell and give the callsignal to station 13. It also shows that the call-bell magnet of substation A is not in the said metallic circuit.

Referring to that portion of the diagram which represents sub-station A it will be found that the condition of the circuit there is, as usual, controlled by the automatic switch H. From any convenient point at on the main line 1 a branch wire 3 leads to the bar 72 of switch H at station A. In the diagram the switch is in its upper position, the receivingtelephone having been removed from its sup port; but in its resting position, the telephone being assumed to be in place, the bar It will make contact with the stop 2", and the calling branch circuit would continueltherefrom by wire 5 through bell D, wire 6, generator Gr, wire 7 to the double key J. It here is united to the stem ilt thereof, which normally presses against its back contact-stop o, and then goes on by wire 23 to the next sub-station B, where it passes by way of a circuit-breaker, shown as a spring-tongue 1/ attached to the under side of the bar of the automatic switch H, and normally making contact with a stop 2', to which the wire 23 is united, a wire 24, a manually-operated key or press-button k its back contact 0 and wire 25 to earth at Q. The call-bell of substation A is thus shown to be in a branch circuit, leaving the mainline wire 1 at n and running to earth at station B. It is necessary that it should be extended to B, in order that B, when using the line for conversation shall not be exposed to interruption by A working his call-generator, and the two circuit-breakers included in the said branch line at B enable B to fully protect himself. The upper one 3 is automatically operated and acts to break the branch circuit whenever B removes his telephone from the switch-bar h, and the lower one k is to be manually operated by B when sending outgoing calls, for a purpose to be hereinafter explained. Therefore, since the callbell of A is in the above-described earth branch, it is evident that whenever the central station desired to signal A the switch S of the generator will be turned to 7., thus grounding one pole of the said generator, and the currents then sent to line will pass over the circuit from the ground at C to the ground at B through the call-bell at A, and will operate the said bell; but the bell at B will not be in this circuit and will not ring.

It is evident that the earth signaling branch might be interchanged from the side 1 to the side 2 of the metallic circuit, provided the earth-switch were also changed to the other side of the generator; but I prefer the arrangement I have described, because it tends to uniformity, for if it be clearly understood that the generator-switch is at all times to be placed on such side of the generator as will tend to make the tip of the plug the line-terminal of said generator, and that the earth branch passing through the bell of station A is always to diverge from line-wire 1, leading to the jack-spring, there will be no opportunity for confusion, especially as in the singleline circuits the line always passes from the spring of the jack and not from the frame.

Both of the sub-stations A and B have clear metallic talking-circuits without any interposed electroanagnets to mar or subdue the quality of the transmitted speech. If A be using the circuit telcphonically, his circuit, as shown, is from the point 12. on line-wire l to the switch-bar it, its upper eontact-piecej, wire 26, transmitter '1, wire 27, receiver 25, and wire 28 to the point 4 on the main line 2, the remainder of the circuit working inward being over the said main wires 1 and 2. If B be using the circuit for talking to some other circuit through the central station, his route is by wire 1 to his automatic switch to the upper contact j thereof, and by wire 29, transmitter T, wire 30, receiver and wire 31 to point 32 on main wire 2, and thereover back to the central station. If A and B wish to talk together, the connections of both are also as described. It is true that when the nearer station is connected for conversation through the central station the distant-station bell is connected in parallel circuit therewith, and also that when the two sub-stations are talking together the central-office annunciator is in parallel circuit with them. These facts are not material in practice, it being well known that the inductive reactions arising from the parallel connection of additional stations practically prevents any loss of workingem-rent. It is also true that when B is connected for conversation through the central station the ground-branch extension is attached to one side of the metallic circuitthe wire 1; but any effect this may have in unbalancing the circuit is minimized by the operation of the automatic circuitbreaker 1 at B, which under such circumstances cuts off the earth terminal from said branch.

Vhen A wishes to send a call to the central station, the press-button u of the circuit;- changer J is pressed, and by this action the normal earth signal branchisbroken between m and 0, the call-instruments at A. are transferred from the said earth branch to the metallic main-line circuit, and the metallic cireuit beyond A leading to B is opened at the pointsj and n, and B cannot, therefore, interrupt the operations of A.

hen B wishes to signal the central station, no other action is absolutely necessary than to operate the generator G, the instruments being already included in the metallic main circuit; but as a matter of precaution, both to prevent an immediately following or simultaneous ring by station A and also to prevent the unintended ringing of the bell at A when B sends the call, which would happen if a ground or escape were on anypart of the wire 2 between M and M, I supply the manual circuit-breaker in the earth branch at B, and I prefer that the operator there while sending a call should press thebutton of said circuit-breaker, and thus open the circuit of the earth branch.

I claim as my invention- 1. A metallic circuit extending between a central and two sub stations, the electro-magnetic call-bell at the most distant sub-station being included directly in said circuit and that of the intermediate sub-station in a branch circuit diverging from one of the wires thereof at said intermediate station and extending to an earth terminal at the outer most station, a call-sending generator at the central station, and a switch therefor determining by its position the connection of said generator in said metallic circuit for the purpose of individually ringing the bell of the most distant sub-station, or in an earth-completed circuit including the branch leading through the call-bell of the intermediate station, for the purpose of operating said callbell.

3. The combination,substantially as hereinbefore described, of a metallic telephonecircuit extending from a central station to two sub-stations, an earth branch extending from one of the wires of said metallic circuit at the intermediate station to earth at the outermost station, call apparatus at the outermost sub-station, included in the said metallic circuit, call apparatus at the intermediate sub-station, included in said earth branch, a call-generator at the said central station, adapted for connection in the said metallic circuit, together with the call apparatus at the outermost substation, and to actuate the same, and switching devices also at the said central station, whereby one terminal of the said generator may be disconnected from the said metallic circuit and transferred to an earth connection, whereby an earth returncircuit is completed through the call apparatus at the intermediate substation for the purpose of operating the same and selectively signaling the said station.

The combination, substantially as here inbefore set forth, in a telephone system,of a metallic telephone-circuit uniting a central station with two sub-stations, to call sending and receiving appliances of the most distant station being normally included directly in the said metallic circuit and those of the nearer or intermediate station being included in an earth branch thereof, as described, a single annunciator included in the metallic circuit at the central station, and a circuitchanging device located at said intermediate sub-station, in its normal position maintaining the continuity of both metallic circuit and earth branch, but capable of being moved into a second position, the call appliances being thereupon transferred to the said metallic circuit from the earth branch for the purpose of operating the central-office annunciator, and the said metallic circuit opened between theintermediate and terminal stations to prevent interference from the latter.

4. The combination of a metallic telephonecircuit extending from a central station to two sub-stations, and call sending and receiving instruments included therein at the most distant substation, a branch circuit diverging at the intermediate sub-station from one of the wires of said metallic circuit and extending to an. earth-terminal at the most distant station, call sending and receiving appliances at the intermediate station normally included in said branch circuit to earth, and a circuit-breaker adapted for manual operation at the most distant station, also included in said branch, whereby the said branch may be discontinued from earth while a signal is being sent from the most distant station, for the purposes herein specified.

5. The combination of a metallic telephone" circuit extending from a central station to two substations and call sending and receiving appliances included directly therein at the outermost of said substations, and a branch diverging at the intermediate sub statiozr from one of the wires of said metallic circuit and extending to an earth connection at the most distant station, the intermediate station call sending and receiving appliances being included therein, with an automatic and manual circuit-breaker included at the most distant station in said branch, the said automatic circuit-breaker being adapted to act during the transmission of conversation and the manual circuit-breaker during the transmission of signals, whereby the said most distant station is enabled to control the continuity of the earth branch circuit, substantially as hereinbefore described, and for the purposes specified.

' 6. The combination of a metallic telephonecircuit extending from a central station through an intermediate to a terminal substation and call sending and receiving instruments included directly therein at the terminal station, and abranch circuit diverging at the intermediate sub-station from one of the wires of said metallic circuit and extending to an earth connection at the terminal station, the intermediate station call apparatus being normally included therein, a spring-jack, and a call-receiving annunciator includ ed in the metallic circuit at the central station, with a circuit-changing switch at the intermediate stat-ion, adapted to transfer the call apparatus from the earth branch to the metallic circuit for the transmission of outgoing signals, an automatic circuit-breaker controlled by the telephoneswitch, included at the terminal station in the earth-branch circuit, and an independent manual circuitbreaker also included therein at the said terminal station, all substantially as described,

. and for the purposes specified.

7. A metallic circuit for telephonic communication connecting a central station serially with two sub-stations, signal sending and receiving apparatus at the terminal sub-station, normally included in the said metallic circuit, a normally-closed branch to earth diverging from one of the main-line wires at the intermediate sub-station and extending to an earth connection at the terminal station, signal sending and receiving apparatus at the intermediate station, normally included in the circuit of the said earth branch, normallyopen telephone branch circuits at each substation, permanently attached at one end to the other main wire and adapted to be closed and to form parts of the metallic circuit main line, that at the intermediate station constituting a bridge from one of the wires of said main line to the other and that at the termi nal station as an alternate section of line for the alarm-inst-ruments, and automatic telephone-supporting switches, one at each substation, to effect said changes and to close said telephone branch circuits, substantially as indicated, and for the purposes specified.

8. A telephone-exchange system comprising, in combination, a metallic telephonc-ciredit extending from a central station to two sub stations, a springjaek at the central station, comprising a metallic socket or frame connected with one of the main wires of said circuit, an insulated contact set in said frame, and a contact-spring forming the terminal of the other main wire, insulated from said frame and bearing on said contact-point, an an u anoiator in a loop from said insulated point to said frame, a branch at each sub-station from the line-wire leading from said eontactspring, said branch extending to the automatic tele phone-supporting switches of said stations, a normally-closed extension of the said branch at the outermost sub-station leading through call apparatus to the main wire l'QPlQSOlltll'lg the spring-jack frame, a normally-closed extension at the intermediate substation leading from said branch there through the signaling-instrumcnts of such station to earth at v the most distant station, a branch at each substation from that wire of the metallic circuit leading from the spring-jack frame, the said branches being normally open and including at each sub-station the telephones thereof, a

generator at the central station, a switch therefor to connect the same with both wires of the metallic circuit or with that one connected with the contact-spring of the spring-jack at will, a circuit-changer at the intermediate substation adapted to transfer the signaling apparatus there from the earth branch to the main circuit for sending outgoing signals, an automatic switch at the intermediate sub-station to disconnect the earth branch and simultaneously to close the telephone branch as a bridge between the two main wires, and a similar switch at the tern'iinal station aeting to disconnect the call apparatus and to substitute the telephones therefor, substantially as described.

111 testimony whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 20th day of June, 1800.

JAMES L. MCQUARRIIC.

Witnesses:

GEo. Wnmts PIERCE, FRANK L. Loenwoon. 

